The invention relates to an improved tie bolt accumulator and a safety venting valve mechanism which insures that the tie bolt accumulator cannot be disassembled until the pressure in the tie bolt accumulator has been vented.
Accumulators have been used for storage of high pressure fluids in hydraulic circuitry. In the past, problems have arisen in the use of these accumulators in that the nitrogen used to pressurized the accumulators is normally obtained from commercial sources and contains moisture. The moisture inside the accumulator can cause rust and other corrosion which will shorten the life of an accumulator. Of great importance in accumulators is their ability to provide for a high pressure source of hydraulic fluid and this necessitates that the piston therein be able to be moved freely.
In the past, accumulators have been made using cylinders which have been welded to end caps to provide a housing for the piston inside the accumulator. The welding of the cylinder to the end caps leaves an area underneath the weld which can contaminate the interior of the cylinder and cause breakdown of the accumulator.
Another known method of making accumulators has the end cap and the cylinder wall screwed to one another. Threading the internal area of the cylinder has caused sharp threads or grooves at the ends of the cylinder which can attack and tear the seals of the piston. This is especially true upon insertion of the piston into the cylinder. Additionally, these types of threaded end caps require large spanner wrenches for removal and the threads can easily be jammed inhibiting cleaning and reusing of the accumulator.
Under both the welded and the screw-in type of accumulator, the ability to clean the accumulator is severely limited. This is true even when one end cap is welded and the other end cap is screwed on. The reason for this difficulty is that where a weld joint between the cylinder and the end cap occur, this also allows for a small space into which debris from the weld can accumulate and eventually contaminate the accumulator. Also, the screw threads attack the cleaning process material and shred it and there is a chance that some of the brushes or other material used to clean the accumulator will be retained inside the cylinder.
Another disadvantage of the welded on type of end cap is that replacement requires replacement of the whole unit and does not allow for replacing only the end cap or the cylinder itself.
Applicant has provided a new type of accumulator which is designed so as to avoid the previously mentioned disadvantages occasioned by screw threads and welding. In applicants' accumulator, a cylinder is slidingly connected to two end caps and tie bolts are extended between the two end caps to hold the cylinder in sealing and abutting relationship to the end caps. In this manner, the tie bolt accumulator is easily disassembled for cleaning purposes and there are no rough edges due to screw threads in the assemblage.
The tie bolts extend on the outside of the tie bolt accumulator and they are held on by nuts at one end. The other end of the tie bolt can be screwed into an end cap of the tie bolt accumulator while the other end is provided with a nut to secure the other end cap. If the tie bolts should rust or corrode into the end caps or if the bolts have their nuts frozen to the bolts themselves, this assembly is still easily opened for cleaning. This opening is obtained by merely sawing the tie bolt and removing it. Thus, the end cap and body are unaffected and may be reused with new tie bolts. Replacement of a tie bolt is a very inexpensive item in servicing an accumulator.
This tie bolt construction has an extreme advantage over the assemblage wherein the cylinder is either welded to, or screwed directly to, the end cap. In those type of devices, the end cap and cylinder of the welded construction have to be replaced as a unit. If the screw threads of the end cap corrode with the cylinder, again one has to replace the whole unit.
In the present invention the tie bolt accumulator end caps have a cylindrical inner surface which is slightly smaller than the cylinder internal diameter. Thus, a seal can be placed on the smaller diameter and the end caps are slid into the cylinder Then the tie bolts are extended through one end cap and threaded into the other end cap. The nuts are screwed onto the ends of the tie bolts to produce a tight assembly.
For cleaning purposes, all one has to do is unscrew the bolts (or their nuts), slide them out, pull of the end caps and all the surfaces that are internal to the tie bolt accumulator are now available for cleaning. None of these surfaces have rough edges and they are therefore easily cleaned.
A further feature resides in the tie bolt accumulator of the invention in that there is a safety mechanism to keep the tie bolt accumulator from being disassembled for cleaning purposes when there is still pressure in the tie bolt accumulator.
It would be extremely dangerous to start to undo the tie bolts when there is high pressure nitrogen inside the accumulator. Accordingly, the invention provides for a venting valve which automatically vents the high pressure nitrogen prior to disassembly of the tie bolts themselves. In this regard, the venting valve is screwed into an end caP of the tie bolt accumulator. When it is desired to disassemble the tie bolt accumulator for cleaning purposes, the vent valve is unscrewed and the nitrogen inside the accumulator is vented around the vent valve.
The venting valve can be attached to a cover which encases the outer edge of the end cap of a tie bolt accumulator. The nuts on the tie bolts are located under this cover. The venting valve is attached to the cover in such a manner that the cover cannot be removed until the venting valve is unscrewed enough to provide for venting of the tie bolt accumulator itself.
After the venting valve has been unscrewed, the cover is either moved outwardly a sufficient distance, such that the nuts on the end of the tie bolts become accessible or the cover is completely removed so the nuts can be unscrewed to disassemble the tie bolt accumulator. Prior to the time the vent is unscrewed, the nuts on the ends of the tie bolts are not accessible. The vent valve can be attached to the cover to cause the cover to move as the vent valve is opened to provide access to the underlying nuts or the vent valve can be separated from the end cap along with the cover.
In order to insure that the vent valve is retained with the cover to cause movement thereof, or to keep the valve in place for reassembly a clip is located on the vent valve between the cover and the end plate, such that the vent valve is retained to the inside of the cover as well as by having the screw head of the vent valve on the outside of the cover. The screw head of the vent valve is larger than the hole in the cover. In assembling the vent valve, it is slid through a hole in the cover and the clip is placed on the inside. Then the cover is placed over top of the end cap and the screw of the vent valve is tightened down to close off the venting passageway. Thus, it can be seen that the vent valve is joined to the cover in such a manner that the cover cannot be removed until the tie bolt accumulator has been vented.
The method for disassembling the tie bolt accumulator is to first unscrew the vent valve a sufficient amount to allow for venting of the nitrogen inside of the accumulator around the vent valve. This unscrewing of the vent valve either raises the cover away from the ends of the tie bolts or allows for its removal. When the cover is removed from the ends of the tie bolts, a wrench can be applied to the nut on the ends of the tie bolts to unscrew them and the tie bolts can then be removed and the end caps slid off from the cylinder. At this point, the whole assemblage can be cleaned or any portion or part thereof can be replaced.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.